Speedometer problem.

[my84bmw325e]

Hello Members,

I bought in August a 1984 BMW 325e with 54,000 original miles. The car is unmodified and has been garaged its whole life. The problem that I am having is a speedometer that has a mind of its own. It could work for days and then go dead for miles. Sometimes if I tap on the cluster lens the gauge wakes up. I changed the lower circuit board because it was preventing the alternator from working. The bad board was also preventing dashboard light to not work. Now all the light and my alternator work but the speedometer is still the same.
Has anyone have the same problem and what did you do to fix it? Thank you.

P.S. I ran a car fax and my mileage is close to accurate. I see on the car fax that this problem started just before I bought the car.

Sincerely,

Patrick

[Dmitry at Pelican Parts]

Hey Patrick- welcome to the forum! I would recommend getting in touch with North Hollywood Speedometer - they are the masters behind these kinds of repairs. Hope this helps you out a bit.

Let us know if you have any other questions.

[my84bmw325e]

Thank you Dmitry.

[tomgalloway1]

Hi Patrick

I just bought a '91 at a good price because / among other things/ the speedo is goofy. The local BMW guru spent ten hours and busted two doner speedos trying to fix it. Tach is OK, MPH and fuel are dead - now its my problem - I bought it.

IMHO - BMW's suffer from corrosion - "the oiley cars run better" is mantra living in moist areas. So my money is on a can of electrical contact cleaner than a can of some silicone or whatever and to check the ground wire / add redundent ground.

Not much on these cars really breaks, dirt & corrosion - is - / could be the pulse sensor (?)

Tom

[my84bmw325e]

Hello Tom,
The speedometer is getting better the more I drive the car. The previous owner only put fifty miles a year on it during its last ten years. I did get a lot of dash lights, alternator etc... to work again by replacing the circuit board in the instrument cluster. Capacitors have a twenty year life span and mine were thirty-five year old.
Patrick

[High Life]

Patrick

Be aware that the plastic speedo gears begin to break /lose teeth. I have rebuilt several of these since I own so many E30's - it is a very common issue for both VDO and Motometer units.

Since you have already changed the circuit board, capacitors and (most likely) the batteries - I would take a quick look at the gears if the problem continues. It is not a difficult job if you decide that is the issue.

Here is where I buy the gears: https://store.garagistic.com/odometer-gears/e30-odometer-repair

There are youtube videos out there to guide you.

The small brown cog often deteriorates first and can start causing intermittent issues..

[my84bmw325e]

Hello High Life,

The previous mechanic replaced all the gears. They left the parts in a little plastic bag and they were all broken up. I notice that the more I drive the car the faster the speedometer (wakes up). The (miles per gallon) needle also has a mind of its own. I stopped tapping the gauge panel because I afraid that I might effect a light bulb. Thank for the information. Patrick